O'Neill and her twin sister Kate left Yale as two of the most decorated athletes in school history. They were both Academic All-Americans as seniors and became the only female runners in Ivy League history to run under 16 minutes in the 5,000 meters as well as the only ones to go below 33 minutes in the 10,000. They were together named the Most Outstanding Performer at the Outdoor Heptagonal Championships in 2003. Between them, they finished first and second in the 3000m, 5000m and 10,000m - finishing within a second of each other in all three events. Kate became the first woman to win the 5000m three straight times and Laura was the first do so in the 10,000m.

Laura earned three All-America honors as a senior in 2002-03. She finished fourth in the 10,000m at the NCAA Outdoor Championships, fifth in the 5000m at the indoor championships and 13th at the cross country championships.

The USA Track and Field Championships, held at the Home Depot Center, hosted more than 1,000 athletes as they competed for the right to represent Team USA at the 2005 IAAF World Championships in Athletics August 6-14 in Helsinki, Finland.